arXiv subjects

D. O. Derecha

Publications and source records attributed to D. O. Derecha.

3 recordsLinked to original sources

arXiv2026

Influence of Elastic Oscillations on Nucleation in Metals

This work is devoted to establishing the mechanisms of elastic oscillation influence on nucleation processes in metal melts. The method of physical modeling with low-temperature metallic alloys (Wood and Rose) and transparent organic media (salol, camphene, diphenylamine) was used. It was established that vibration and ultrasound significantly reduce the supercooling required to initiate crystallization. The effectiveness of the influence significantly increases for samples with solid substrates. The hypotheses about the influence through changes in melt viscosity and the exclusive role of cavitation were experimentally refuted. The transition from pre-cavitation to cavitation ultrasound regime is not accompanied by qualitative changes in the influence on nucleation. The mechanism of elastic oscillation influence is substantiated, which consists in mechanical impact on adsorbed crystal nuclei on the surfaces of solid substrates. Elastic oscillations increase the nucleation rate by creating growth steps (dislocations) on the surfaces of adsorbed nuclei as a result of mechanical friction of solid substrates and cavitation erosion. The results have fundamental significance for understanding the physical nature of metal crystallization and practical application for developing technologies for controlling structure formation.

cond-mat.mtrl-sci↗

arXiv2025

The size effect on nucleation process during solidification of metals

This work investigates the mechanisms of crystal nucleation in metal melts, in dependence on the influence of their shape and volume. Investigations were conducted on both thin flat and bulk samples prepared of low-temperature Wood's metal alloy and transparent organic media (camphene and diphenylamine). The study revealed that in flat samples, the nucleation rate is primarily influenced by the activity of the mold wall surface, which is affected by melt overheating and subcooling, while in bulk samples, supercooling and nucleation are additionally influenced by factors such as impurity activity, temperature, and density fluctuations.

cond-mat.mtrl-sci↗

arXiv2024

Physical simulation of nucleation and crystallization processes in transparent organic melts

The aim of this work is the development of scientifically based ways of influencing the process of nucleation of crystallization centres to control the cast structure and the properties of blanks at the casting stage. The possibility of controlling crystal nucleation was studied on transparent modelling media using the droplet method. The dependence of the crystallization kinetics of drops with a size of 100÷200 μm on the overheating temperature, the exposure in the overheated state and the degree of supercooling was established. The curves of the crystallization kinetics of drops from their melts as the criteria for evaluating the crystallization process were chosen. The nature of the change in the experimental media crystallization kinetics curves confirms the assumption about the decisive role of impurities in the crystallization processes of any alloys. The confirmation of the hypothesis about the decisive role of impurities in the processes of crystallization from positions of heterogeneous nucleation is the dependence of the number of solidified drops with the same diameter on the degree and duration of their overheating.

cond-mat.mtrl-sci↗